The Science of Birds - The Northern Cardinal

Episode Date: May 6, 2022

This is Episode 51. Our bird of interest today is the Northern Cardinal, Cardinalis cardinalis.This species is widespread across the eastern and southern US. It’s so well-known and loved that it’s the state bird for 7 states—more than any other species.Northern Cardinals are among the most abundant birds in North America. They’re familiar denizens of backyards that visit feeders all year long. So it shouldn’t be surprising to hear that ornithologists have done a lot of research on this abundant and conspicuous species.~~ Leave me a review using Podchaser ~~Link to this episode on the Science of Birds websiteSupport the show

The first time I saw a northern cardinal in the wild, I was thrilled to finally see this gorgeous and iconic red bird in the flesh. Until then, I had seen only photos and Christmas card illustrations of cardinals. That's because I grew up on the west coast of the U.S., far outside the natural range of this species. It was in North Carolina that I saw. my first cardinal. A friend and I were attending a scientific conference there, and we snuck away to do a little birding on the side. My friend was a far more experienced and serious birder than I was at the time. So there I am, all excited to see my first Northern Cardinal, when my friend almost

ruins the moment by dismissing it as a trash bird. Buzzkill much? Trashbird is birder-ling. for a species so frequently encountered in the local area, one so common that it's uninteresting and pretty much worthless. It's trash. That was the first time I heard the term. I was shocked, shocked and appalled. I mean, aren't birders supposed to be people who love nature and appreciate birds? How could anyone think of the amazing Northern Cardinal as trash? Well, here I am 20 years later. I too am what some might call a serious birder now. But I still don't like the term trash bird. I'm not into it. And even though I've seen a bunch of Northern Cardinals over the years, I still love them. Today, we're going to chat about the

natural history of this charming red bird. Hopefully, you won't need much convincing that the Northern Cardinal is anything but worthless. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson. The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. This is episode 51.

Our subject today is the Northern Cardinal, which has the scientific name of Cardinalis, Cardinalis. That one is pretty easy to remember, right? Cardinalis, Cardinalis. This species was actually chosen for this episode by my supporters on Patreon. One perk of being a patron is that you get to vote in polls. I asked my patrons to choose between two species. and the Northern Cardinal won. If you want to vote in polls like this,

consider becoming a patron. For details, check out my Patreon page at patreon.com forward slash science of birds. The Northern Cardinal is a North American species. It's widespread across the eastern and southern U.S. It's so well known and loved that it's the state bird for seven states. That's more than any other species.

Sorry, Western Meadowlark, but you're in second place. The Northern Cardinal is also the team mascot for the Arizona Cardinals in the NFL and the St. Louis Cardinals in Major League Baseball. Not too bad for a trash bird, eh? Northern Cardinals are among the most abundant birds in North America. They're familiar denizens of backyards that visit feeders all year long. So it shouldn't be surprising to hear that ornithologists have done a lot of research on this abundant and conspicuous species. Let's start with the basic appearance of the Northern Cardinal.

This is a medium-sized songbird at about nine inches long, from beak to tail. It sports a pointy, triangular crest on its head. Northern cardinals raise or lower their crests to communicate their mood. For example, it seems they often lower and flatten their crests in many aggressive encounters with other birds. So if a cardinal looks at you and flattens its crest, look out. You should interpret that as the bird saying, I kill you! The major claim to fame for this bird is, of course,

course, it's plumage color. The male northern cardinal is a bright red overall, like absurdly red. His head and breast have the most saturated color, the sort of glowing red that almost hurts your eyes to look at. The back and upper wings, on the other hand, are a little more dull. Male cardinals also wear a black mask around the base of their bill and eye. The female isn't as brightly colored, but she, too, is a lovely little beast. The female is a buffy gray all over, but with some muted red highlights in the crest, wings, and tail. Her mask is much less obvious. The name, cardinal, is a reference to the bird's red color.

In the Catholic Church, you got the Pope at the top, then below him in the pecking order, in what ornithologists might call the dominance hierarchy, see episode 48, are the Cardinals. These dudes, the Cardinals, traditionally wore rich red robes and hats, so there you go. An assortment of scientific studies on Northern Cardinals has found correlations between the red and black plumage coloration of individual birds and other traits like reproductive success and behavior. Unlike so many other familiar songbirds, the Northern Cardinal doesn't swap out its bright feathers for dull ones in winter. This species looks pretty much the same all year long. Now, you might take it for granted that a red bird like the Northern Cardinal is simply born that

color. Simply Red. Like the British pop star dude from the 80s. Remember Simply Red? If you're under 45 years old, I bet you don't. Or maybe you wish you didn't remember simply red. Who knows? Anyway, you might assume that the red color of adult cardinals comes from a pigment produced by the birds themselves, as though their bodies can create the color red out of thin air. But that's not the case. Most of the world's red, orange, or yellow birds, that is, birds with warm colored plumage, get their vibrant colors from the things they eat. particularly from plants, seeds, leaves, and fruit. Plants make pigments called carotenoids.

You can hear the word carrot in there. Carrots are orange because they're chock full of carotenoids. The Northern Cardinal eats seeds and small fruits mostly. Many of these have yellow and orange carotenoid pigments. But the bird is red, right? Not yellow or orange. The reason is that, at the molecular level, northern cardinal converts those yellow carotenoids into red pigments using a special enzyme.

Then the newly created red pigment is deposited in the growing feathers. Every so often, someone spots a northern cardinal in their backyard or in the woods that's bright yellow instead of red. Word spreads and then people freak out. Thousands of birders and other novelty seekers jump in their cars and speed off to go see the yellow cardinal. A few years ago, there was a yellow cardinal in Alabama that was given the name Mr. Yellow. So much for creativity, I guess. Actually, I really like that name. It sounds sort of like a Bond villain name.

Mr. Yellow. Anyway, Mr. Yellow soon became a celebrity. People kept tabs on him and cheered as he found a mate and raised some chicks with her. Interestingly, none of the chicks turned out yellow. So what's the deal with Mr. Yellow? Ornithologists think yellow cardinals like this are born with a one-in-a-million genetic mutation. It prevents yellow carotenoids from being converted into red pigments in the bird's cells. The mutation might be a simple change of one base pair in the gene that codes for the special enzyme I mentioned.

The enzyme that converts yellow to red, right? If that enzyme is all wonky and doesn't work as it should, yellow pigments from plant foods may just stay yellow and they get deposited in the feathers. This phenomenon actually has a name. Biologists call it Xantho-Croism. When you hear the root word Xantho, think yellow. The rare phenomenon of Xantho-Croism has been recorded in some other birds that are normally red, like the red-bellied woodpecker in North America, and the crimson-breasted gonaleck in Africa and the Scarlet Robin in Australia. Another rare and strange thing people sometimes see in their backyard is a northern cardinal

with a bald head. As in, the bird has no feathers on its entire head and neck. This is just fantastic. It's hilarious. Do yourself a favor and Google bald northern cardinal right now. These poor little birds look like sad, tiny vultures. Without their head feathers, you can see just how much volume the feathers normally add. Underneath the feathers, a soft songbird's head is much smaller than you'd think. Anyway, ornithologists aren't exactly sure why this baldness thing happens. But it seems to be just the normal molting process, except that all the head feathers fall out at once.

These microvulchers eventually grow new head feathers, and they soon go back to looking normal and less hilarious. Now, one thing I haven't mentioned yet is the bill of the Northern Cardinal. The bill is stout and cone-shaped. It's a red-orange color in adults and gray or black in juveniles. And that leaves one more key trait to talk about, and that's the song of the Northern Cardinal. The song is a pleasant, clear-toned string of whistles and trills.

Some have described the song of the Northern Cardinal phonetically as sounding like, What? Cheer, cheer, cheer! The following example might fit that pattern to some degree. Another song variation is given as, cheer, cheer, what, what, what, what, birdie, birdie. I think this one sort of follows that pattern. Sort of. And here's another example.

This next song is really bright and has some major trilling going on. And here's an example of a simple call rather than a song. This is the Northern Cardinal's Chip Call. is unusual among North American songbirds because the female also sings quite a lot. The last episode of the podcast, Episode 50, was about female bird song, and I briefly mentioned Cardinals. So far, I've been playing you the songs of male Northern Cardinals. In some cases, the female Cardinal may actually have a longer and more complex song than the male. Here's a female Northern Cardinal singing.

And I realized that song wasn't all that long or complex, but that's the only female cardinal song I could get my hands on. Interestingly, though, a bonded pair of Northern Cardinals will often share some elements of their songs, a little phrase here or there, for example. But I'm not sure anyone has a full explanation for why Northern Carnal's. Cardinal females sing, while so many other North American songbird females don't. The results of at least one study suggested that females sing while sitting on the nest to request food from their mates. So maybe one function of female songs in Northern Cardinals

might be to get food delivered, sort of like the bird version of the DoorDash or Grubhub app. This busy working mom doesn't have time to make a run to the grocery store, much less prepare a meal for her hungry family. Luckily for her, there's Grubhub. The female Cardinal simply sings a sweet song from the comfort of her nest. Within minutes, her dutiful husband swoops home to deliver a steaming beakful of,

you guessed it, grubs. And in case you're wondering, this podcast is not sponsored by Grubhub. How about we talk a little about the relationships between the Northern Cardinal and other birds? Then we'll look at the Cardinal's distribution and its habitat. This species is a member of the biological family, Cardinality. The 49 bird species in this family are all found across the new world. Three of them, including today's featured creature, are in the genus Cardinalis.

The other two are the Vermilion Cardinalis. Cardinalis Phoenisius, and the Paraloxia, Cardinalis Cynuatus. So these two bird species would be considered the closest relatives of our northern cardinal. The latter is found further north than the other two species, so that's why it's called the Northern Cardinal. Vermillion Cardinals live in the extreme north of South America. The Paraloxia is a bird of arid places in the southwestern part of North America. Its range actually overlaps that of the Northern Cardinal in Texas, New Mexico, and Arizona.

I think of Piroloxias as basically desert cardinals. There's a lot of variation among populations of the Northern Cardinal. So I'm talking now about within species variation. According to ornithologists, there are between 18 and 19 subspecies of Northern Cardinal across North America. These subspecies are distinguished by differences in bill shape and size, the length of the crest feathers, the extent of the black mask on the face, overall color, body dimensions, song dialects, political views, and so on. So now I invite you to settle in and get comfortable

as I painstakingly describe the unique characteristics of each and every one of the 19 Northern Cardinal subspecies. Don't worry, this should take only about two hours. And pay close attention because there will be a test at the end. You could tell I was kidding from the get-go, couldn't you? You could hear the puckish tone that crept into my voice as I switched into high-comedy mode. No, I'm not going to drag you through a boring treatise on Northern Cardinal subspecies. But you should know that besides there being measurable physical differences among the many subspecies, there are also some genetic differences.

A 2011 study published in the journal BMC Ecology and Evolution analyzed mitochondrial DNA data to sort Northern Cardinal specimens into six distinct genetic groups. These groups are also geographically separated from each other. For example, there are several groups unique to distinct parts of Mexico. Looking again at the Northern Cardinal species, species as a whole, we see it has a wide distribution across the continent. The core of its range is in the southeastern United States. Once upon a time, back in the 1800s, this species

had a different scientific name. It was Cardinalis Virginianus. That was in acknowledgement of the bird's southern affinity. But even in the 1800s, the northern cardinal was beginning to expand its range northward. By 1900, they were common as far north as New York, but the expansion didn't stop there. The fluttering horde of red birds marched on. Now the northern cardinal is found well up into Quebec in Canada. From Quebec to southern Mexico, you can find northern cardinals in all sorts of habitats, in suburban hedges and parks, shrubby grasslands, forest edges, desert scrub, and more. The common feature of all of these habitats seems to be shrubs. Cardinals need woody plants with dense foliage, especially during the nesting season.

But their habitat needs aren't all that different in the non-breeding-slash-winter season. That's because the Northern Cardinal doesn't migrate. It's a year-round resident wherever you find it. I didn't know that when I first ran into Northern Cardinals in Oaxaca, Mexico. I thought for sure those little dudes were migrants from. far to the north. But nope, they live on the coast of southern Mexico all year long. The non-migratory, or some might say the non-migratory, nature of the Northern Cardinal, is one reason that it's such an iconic winter bird in the U.S.

When the landscape turns all white and fluffy with snow, we've got these bright red birds bouncing around out there. They're a cheerful sight, a splash of rich color in a world that's mostly monochrome. Northern cardinal images have become almost obnoxious during the Christmas holiday season. Depictions of these birds show up as tree ornaments, they're plastered across Christmas cards and ugly sweaters, and they're imprisoned inside of tacky snow globes. Well-meaning grandmas across the nation are to blame for supporting the bustling trade in cardinal-related Christmas schlock. But seriously, ladies, enough is a enough. Many other colorful songbirds that breed in North America head south to the tropics

in winter. Those species tend to eat mostly insects, which pretty much disappear from northern landscapes in winter. The northern cardinal, however, can stick around all year in the north because it thrives on a diet of seeds. If you know where to look, you can find seeds here and there, no matter what season it is. And hey, it turns out, seeds are even easier. to find than they used to be. If you're a Northern Cardinal these days, all you might need to do is bop over to some humans' house and gorge yourself on the cornucopia of seedy goodness that miraculously gets replenished every day. Besides the effects of good old global warming, the Northern Cardinal might be expanding its range because of this steady supply of seeds in backyard feeders.

and yet another factor is that humans have created more brushy habitat for cardinals. Pesky humans have also directly interfered with the range of the Northern Cardinal. We've introduced these birds to the islands of Hawaii and Bermuda and probably a few other places. I'm happy to report that the Northern Cardinal is not endangered or under any major threats at the moment. The species is in the least concern category of the IUCN Red List. Once upon a time, however, the outlook wasn't so good for the Northern Cardinal. Wild Cardinals used to be trapped and sold as cagebirds, because they're pretty and they have pleasant songs. Thousands of them were shipped overseas for the cagebird trade. Thankfully, that practice came to a

grinding halt, more or less in the early 1900s with the Migratory Bird Treaty Act. Without that law to protect Cardinals, who knows what their fate might have been. Unlike so many of our native bird species, Northern Cardinals appear to be benefiting from the way humans change habitats. Humans have created more shrubby habitats across North America by cutting down forests and all of that. Cardinal populations these days might actually be larger than they were before Euro-Americans came along to tear things up. For this bird, life is apparently pretty good. The Northern Cardinal is an opportunistic feeder. These birds do love seeds, and that conical bill they have is well adapted for crushing and cutting seeds shells.

But these birds also eat other plant material like the fruits of wild grape, dogwood, mulberry, and so on. They eat lots of other seeds and fruits, including domestic corn and oats. In summer, Northern Cardinals forage in broad-leaved trees and shrubs, looking for insects. About 30% of their diet comprises small invertebrates. When there are chicks in the nest, the parents feed them a diet of pretty much all insects. Northern Cardinals are among the most familiar backyard birds across a large swath of the U.S. They love gorging on the seeds we put out for them. For some reason, Northern Cardinals tend to visit feeders first thing in the morning and at dusk.

And speaking of feeders, there was this awesome scientific study published a few years ago in the journal Behavioral Ecology. I think I've mentioned it before. The researchers used tons of citizens. science data from backyard bird feeders to rank 136 bird species across North America, ranked in terms of their dominance. This tells us which bird species tend to be victorious in interspecies squabbles at the feeder. From the results of this study, it appears the Northern Cardinal has an intermediate rank. Northern Cardinals tend to lose their fights against woodpeckers, blue jays, and starlings.

But Cardinals bully smaller birds like chickadees, nuthatches, and finches. When it comes to breeding, Northern Cardinals are monogamous. Well, they're socially monogamous anyway. Remember what that means? It means that even though a mated pair of Cardinals sticks together to raise a family, the male or the female might sneak off to mate with other birds on the side. In a couple of studies, it was found that 9 to 35% of the chicks in a cardinal nest resulted from matings outside of the parents at that nest.

So we'd say those nestlings were the products of extra pear fertilizations. To the outside world, mated pairs of cardinals appear to be faithful to each other. they have such wholesome family values. But it's all a sham, I tell you. The birds are deceiving each other and they're deceiving us. How shameful. Actually, we probably shouldn't be too judgy. First off, we humans don't have a great track record for fidelity in our monogamous relationships. Ahem. Also, as I've pointed out before, social monogamy is common among songbirds. For them, it's pretty much the norm. The Northern Cardinal is actually among the more faithful songbird species. Pears generally stick together for life, and the extent of extra pair fertilizations, of

naughty shenanigans on the side, is lower in this species than in many other songbirds. When a pair of Northern Cardinals first forms, there is a lot of courtship behavior. The male performs several displays for the female. To impress her, he busts out his lopsided display and his song dance display. The female, too, has some displays of her own. Once the pair has bonded, it's common for the male to offer food to the female. This behavior is called courtship feeding. He feeds her tasty morsels beak to beak before mating and continues to do so once she's incubating her eggs on the nest. Northern Cardinals are highly territorial.

A mated pair usually stays on a territory all year. They defend it fiercely from other birds. To establish and maintain their territory, both the male and female sing and posture from conspicuous perches. They chase off any interlopers and fight them claw to claw when they have to. In spring, Northern Cardinals get all. hopped up on a cocktail of hormones flowing in their blood. They are extra belligerent and territorial during this season.

That's why a Northern Cardinal will sometimes go berserk and attack its own reflection in a car window or a mirror. A Northern Cardinal in hormone beast mode like this might keep fighting its own reflection for days or even weeks. The Cardinal is like, Are you looking at me? Who you calling Trash Bird? Your mom's a trash burn.

Oh yeah? Oh yeah? You want to throw down? Let's do this. Come at me, bro. I kill you. To be fair, this roid rage behavior isn't unique to Northern Cardinals. As I'm recording this episode, right now there is an American Robin attacking its own reflection in my window downstairs. I'm actually hoping the microphone doesn't pick up the sounds of his tiny claws scraping the glass. This psychotic robin thing is an annual event here at the Philipson House. Anyway, when Northern Cardinals can keep their cool long enough to actually raise some babies, they do so in a bowl-shaped nest. In other words, a cup nest.

The ideal site for the nest is among the dense twigs of a shrub or small tree. An average nest has about three eggs. Northern Cardinals have bi-parental care. In other words, both sexes care for the babies. Male cardinals are exceptionally awesome dads. The male feeds his mate and his chicks, and he defends the nest from predators. Male northern cardinals have such strong paternal instincts that they are sometimes seen feeding the chicks of other species. For example, male cardinals have been seen feeding baby rose-breasted gross beaks.

The latter species, the rose-breasted grosbeak, is also in the family cardinality. Most likely, this behavior happens because the Grosbeak chicks or whoever are begging frantically for food. The male Northern Cardinal gets confused, and his powerful instinct to stuff bugs into the gaping mouths of begging chicks just takes over. It's like my powerful instinct to eat ice cream. Sure, most of the time I'll do what I'm supposed to and eat only my ice cream. But if your bowl of ice cream is just sitting there, it's just sitting there right next to me and no one is doing anything about it. I mean, it's not getting any colder, you guys. In that case, I might get confused like a male Northern Cardinal and eat your ice cream too.

He sees a bunch of baby bird mouths and he drops some bugs in there. I see a bowl of unattended ice cream within arm's reach. I eat it. That's just how nature works, right? As for baby cardinals, they leave the nest after one or two weeks. They can fly pretty strongly at this stage, but they stay close to the nest for maybe another 11 days or so. The parents will keep feeding their young for up to two months after fledging.

Then the juvenile cardinals are on their own. The lifespan for a wild Northern Cardinal seems to be about three to six years. The oldest wild individual on record was 15 years old. But the oldest Northern Cardinal that lived in captivity was an amazing 28.5 years old. Life may be good for the Northern Cardinal as a species, but that doesn't mean that life is easy for each individual. To live a long, successful life, a cardinal has to face the many dangers of predators and harsh weather. It has to find a mate and defend its territory from competitors.

Competitors like, you know, that doppelganger bird in the window who looks exactly the same as you and somehow perfectly mirrors your every move, the only thing you can do is attack that guy again and again until you're victorious. I hope you enjoyed learning some fun facts about the Northern Cardinal. I think you'd agree that this species is not a trash bird. What's the opposite of trash? Treasure? I'd say the Northern Cardinal is more of a treasure bird. And seriously, can we please get rid of the term trash bird altogether?

I mean, if being common and abundant makes you trashy, maybe we should call humans trash apes, right? Anyway, thanks for hanging out with me today for some bird learnings. As always, I want to thank my wonderful supporters on Patreon. You are the grease in the wheels, the fuel for the fire, the seeds that fill the crop of this podcast. You make the magic happen. And here's a shout out to my newest patrons. Adam Knight, Wyatt Larson, Ivan Raymond, cool name,

Kayla Shaw, Kylie Warren, and Wendy Layden. Cheers to all of you, and thank you so much for your support. If you, my fellow bird nerd, are interested in supporting this podcast, you can check out my Patreon page at patreon.com forward slash science of birds. You can also shoot me an email if you have something you'd like to share with me. Maybe your thoughts about the podcast, or you want to tell me about your collection of tacky,

bird-themed snow globes. In any case, my email address is Ivan at Scienceofbirds.com. You can check out the show notes for this episode, which is number 51, on the Science of Birds website, scienceofbirds.com. This is Ivan Philipson, wishing you a lovely week. Cheers.